Semiconductor device manufacturing often includes one or more polishing or planarization steps following material deposition on the device side of a substrate. For example, polishing pads are often used to polish and/or abrade a layer of deposited material in a process known as chemical mechanical polishing/planarization or CMP. The polishing surface of a polishing pad must occasionally be conditioned or ‘roughened’ in order to maintain the efficiency with which it polishes or removes deposited material from a substrate. For this purpose, apparatus have been developed and utilized which abrade the polishing surfaces of polishing pads with coarse conditioning material. For example, apparatus exist which condition polishing pads in the presence of an abrasive polishing fluid such as a microabrasive slurry (used to facilitate substrate polishing) on the polishing surface while causing a conditioning surface of a conditioning disk to press against and rotate relative to the polishing surface in a process also known as in situ pad rejuvenation or pad dressing.
Such conditioning apparatuses often employ conditioning heads comprising end effectors adapted to receive and retain conditioning disks. The conditioning head may be adapted to generate or at least transmit a torque to the end effector so as to rotate the end effector and the conditioning disk during pad conditioning. In addition, a down force may be generated, e.g. local to the conditioning head via pneumatic actuation, or remotely (e.g., via a mounting arm), so as to produce the desired degree of frictional interaction between the conditioning head and the polishing pad. The microabrasive slurry, however, has been known to invade such conditioning heads, e.g., in one or both of a liquid and a vapor form, doing damage to internal components such as bearings. Also, some apparatus, carefully designed to generate a desired degree of down force and/or material removal, nevertheless create manufacturing problems, such as imprecise conditioning brought about by poor rigidity, and/or scoring damage to the polishing pad's processing surface as a result of end effectors designed to reciprocate relative to their conditioning heads becoming frozen or locked-up, sometimes in cockeyed orientations not apparent until after the damage has been done.
Semiconductor manufacturing processes are more and more often demanding quicker pad conditioning, lower down forces, and higher rotation speeds for conditioning pads. As a result, effective methods and apparatus for reliably conditioning polishing surfaces of polishing pads, especially methods and apparatus offering good controllability and reliability, as well as high precision, are both desirable and necessary.